The aims of this study were to clarify the histological features of adenoid basal carcinoma (ABC) and determine whether cytokeratin 17 (CK17) and Ki-67 can facilitate the differential diagnosis of ABC from squamous cell carcinoma (SCC).
Nine cases of pure ABC were collected from the files of the Division of Pathology at the Zhejiang University Hospital Women's School of Medicine. For comparison, 20 cases of moderately to poorly differentiated cervical SCC, including 2 of basaloid SCC, were also retrieved from the same period. Blocks were recut, reread, and immunostained for CK17 and Ki-67.
Morphologically, ABCs were mainly composed of small basaloid cell nests and variable squamous differentiation foci. For immunohistochemical staining, 1 of 9 cases showed diffuse CK17 staining, 5 of 9 showed focal positive staining, and 3 of 9 showed negative staining in the basaloid cell area of ABC, whereas no CK17 expression was found in ABC squamous foci. Eighteen of the 20 invasive SCCs showed diffuse CK17 staining, and 2 showed focal staining. The Ki-67 proliferative index varied in different ABC areas, with a relatively high index in squamous differentiation foci and a low index in basaloid cell areas. In contrast, Ki-67 staining was unevenly intense in SCC.
Adenoid basal carcinoma had characteristic morphological features, and the differential diagnosis of ABC from SCC is usually simple, based on morphology. In select cases, when histological findings are equivocal, the loss of CK17 expression in the squamous differentiation area, and a lower Ki-67 index in basal cell foci support ABC diagnosis.
Department of Surgical Pathology, the Affiliated Women's Hospital, School of Medicine, Zhejiang University. Zhejiang Province, China
Correspondence to: Yun Liang, MD, Department of Pathology, the Affiliated Women's Hospital, School of Medicine, Zhejiang University. No 1 Xueshi Rd, Hangzhou, Zhejiang Province 310006, PR China. E-mail: firstname.lastname@example.org
The authors have declared they have no conflicts of interest.
This study was supported by National Key R&D Program of China 2016YFC1302900.
This study was approved by the review board of the Affiliated Women's Hospital, School of Medicine, Zhejiang University, and all patients gave written informed consent for their information to be stored in the hospital database and used for research.